Oxygen toxicity causes cyclic damage by destabilizing specific Fe-S cluster-containing protein complexes.

Oxygen is toxic across all three domains of life. Yet, the underlying molecular mechanisms remain largely unknown. Here, we systematically investigate the major cellular pathways affected by excess molecular oxygen. We find that hyperoxia destabilizes a specific subset of Fe-S cluster (ISC)-containing proteins, resulting in impaired diphthamide synthesis, purine metabolism, nucleotide excision repair, and electron transport chain (ETC) function. Our findings translate to primary human lung cells and a mouse model of pulmonary oxygen toxicity. We demonstrate that the ETC is the most vulnerable to damage, resulting in decreased mitochondrial oxygen consumption. This leads to further tissue hyperoxia and cyclic damage of the additional ISC-containing pathways. In support of this model, primary ETC dysfunction in the Ndufs4 KO mouse model causes lung tissue hyperoxia and dramatically increases sensitivity to hyperoxia-mediated ISC damage. This work has important implications for hyperoxia pathologies, including bronchopulmonary dysplasia, ischemia-reperfusion injury, aging, and mitochondrial disorders.

An EZH2-dependent transcriptional complex promotes aberrant epithelial remodelling after injury.

Unveiling the molecular mechanisms of tissue remodelling following injury is imperative to elucidate its regenerative capacity and aberrant repair in disease. Using different omics approaches, we identified enhancer of zester homolog 2 (EZH2) as a key regulator of fibrosis in injured lung epithelium. Epithelial injury drives an enrichment of nuclear transforming growth factor-ß-activated kinase 1 (TAK1) that mediates EZH2 phosphorylation to facilitate its liberation from polycomb repressive complex 2 (PRC2). This process results in the establishment of a transcriptional complex of EZH2, RNA-polymerase II (POL2) and nuclear actin, which orchestrates aberrant epithelial repair programmes. The liberation of EZH2 from PRC2 is accompanied by an EZH2-EZH1 switch to preserve H3K27me3 deposition at non-target genes. Loss of epithelial TAK1, EZH2 or blocking nuclear actin influx attenuates the fibrotic cascade and restores respiratory homeostasis. Accordingly, EZH2 inhibition significantly improves outcomes in a pulmonary fibrosis mouse model. Our results reveal an important non-canonical function of EZH2, paving the way for new therapeutic interventions in fibrotic lung diseases.

Differential proteomics of Zika virus (ZIKV) infection reveals molecular changes potentially involved in immune system evasion by a Brazilian strain of ZIKV.

Zika virus (ZIKV) is an arbovirus that was responsible for multiple outbreaks from 2007 to 2015. It has been linked to cases of microcephaly in Brazil in 2015, among other neurological disorders. Differences among strains might be the reason for different clinical outcomes of infection. To evaluate this hypothesis, we performed a comparative proteomic analysis of Vero cells infected with the African strain MR766 (ZIKVAFR) and the Brazilian strain 17 SM (ZIKVBR). A total of 550 proteins were identified as differentially expressed in ZIKVAFR- or ZIKVBR-infected cells compared to the control. The main findings included upregulation of immune system pathways (neutrophil degranulation and adaptive/innate immune system) and potential activation of immune-system-related pathways by ZIKVAFR (mTOR, JAK-STAT, NF-κB, and others) compared with the ZIKVBR/control. In addition, phagocytosis by macrophages and engulfment of leukocytes were activated in ZIKVAFR infection. An in vivo analysis using an immunocompetent C57BL/6N mouse model identified interstitial pneumonia with neutrophil infiltration in the lungs only in mice infected with ZIKVBR at 48 hours postinfection, with a significant amount of virus detected. Likewise, only animals infected with ZIKVBR had viral material in the cytoplasm of lung macrophages. These results suggest that activation of the immune system by ZIKVAFR infection may lead to faster viral clearance by immune cells.

Proteomics of Rat Lungs Infected by Cryptococcus gattii Reveals a Potential Warburg-like Effect.

Cryptococcus gattii is the causative agent of cryptococcosis infection that can lead to pneumonia and meningitis in immunocompetent individuals. The molecular basis of the pathogenic process and impact on the host biochemistry are poorly understood and remain largely unknown. In this context, a comparative proteomic analysis was performed to investigate the response of the host during an infection caused by C. gattii. Lungs of experimentally infected rats were analyzed by shotgun proteomics to identify differentially expressed proteins induced by C. gattii clinical strain. The proteomic results were characterized using bioinformatic tools, and subsequently, the molecular findings were validated in cell culture and lungs of infected animals. A dramatic change was observed in protein expression triggered by C. gattii infection, especially related to energy metabolism. The main pathways affected include aerobic glycolysis cycle, TCA cycle, and pyrimidine and purine metabolism. Analyses in human lung fibroblast cells confirmed the altered metabolic status found in infected lungs. Thus, it is clear that C. gattii infection triggers important changes in energy metabolism leading to the activation of glycolysis and lactate accumulation in lung cells, culminating in a cancerlike metabolic status known as the Warburg effect. The results presented here provide important insights to better understand C. gattii molecular pathogenesis.

Proteome profiling of triple negative breast cancer cells overexpressing NOD1 and NOD2 receptors unveils molecular signatures of malignant cell proliferation.

BACKGROUND: Triple negative breast cancer (TNBC) is a malignancy with very poor prognosis, due to its aggressive clinical characteristics and lack of response to receptor-targeted drug therapy. In TNBC, immune-related pathways are typically upregulated and may be associated with a better prognosis of the disease, encouraging the pursuit for immunotherapeutic options. A number of immune-related molecules have already been associated to the onset and progression of breast cancer, including NOD1 and NOD2, innate immune receptors of bacterial-derived components which activate pro-inflammatory and survival pathways. In the context of TNBC, overexpression of either NOD1or NOD2 is shown to reduce cell proliferation and increase clonogenic potential in vitro. To further investigate the pathways linking NOD1 and NOD2 signaling to tumorigenesis in TNBC, we undertook a global proteome profiling of TNBC-derived cells ectopically expressing each one of these NOD receptors. RESULTS: We have identified a total of 95 and 58 differentially regulated proteins in NOD1- and NOD2-overexpressing cells, respectively. We used bioinformatics analyses to identify enriched molecular signatures aiming to integrate the differentially regulated proteins into functional networks. These analyses suggest that overexpression of both NOD1 and NOD2 may disrupt immune-related pathways, particularly NF-κB and MAPK signaling cascades. Moreover, overexpression of either of these receptors may affect several stress response and protein degradation systems, such as autophagy and the ubiquitin-proteasome complex. Interestingly, the levels of several proteins associated to cellular adhesion and migration were also affected in these NOD-overexpressing cells. CONCLUSIONS: Our proteomic analyses shed new light on the molecular pathways that may be modulating tumorigenesis via NOD1 and NOD2 signaling in TNBC. Up- and downregulation of several proteins associated to inflammation and stress response pathways may promote activation of protein degradation systems, as well as modulate cell-cycle and cellular adhesion proteins. Altogether, these signals seem to be modulating cellular proliferation and migration via NF-κB, PI3K/Akt/mTOR and MAPK signaling pathways. Further investigation of altered proteins in these pathways may provide more insights on relevant targets, possibly enabling the immunomodulation of tumorigenesis in the aggressive TNBC phenotype.

Histone chaperone HIRA, Promyelocytic Leukemia (PML) protein and p62/SQSTM1 coordinate to regulate inflammation during cell senescence.

Cellular senescence, a stress-induced stable proliferation arrest associated with an inflammatory Senescence-Associated Secretory Phenotype (SASP), is a cause of aging. In senescent cells, Cytoplasmic Chromatin Fragments (CCFs) activate SASP via the anti-viral cGAS/STING pathway. PML protein organizes PML nuclear bodies (NBs), also involved in senescence and anti-viral immunity. The HIRA histone H3.3 chaperone localizes to PML NBs in senescent cells. Here, we show that HIRA and PML are essential for SASP expression, tightly linked to HIRA's localization to PML NBs. Inactivation of HIRA does not directly block expression of NF-κB target genes. Instead, an H3.3-independent HIRA function activates SASP through a CCF-cGAS-STING-TBK1-NF-κB pathway. HIRA physically interacts with p62/SQSTM1, an autophagy regulator and negative SASP regulator. HIRA and p62 co-localize in PML NBs, linked to their antagonistic regulation of SASP, with PML NBs controlling their spatial configuration. These results outline a role for HIRA and PML in regulation of SASP.

A BioID-Derived Proximity Interactome for SARS-CoV-2 Proteins.

The novel coronavirus SARS-CoV-2 is responsible for the ongoing COVID-19 pandemic and has caused a major health and economic burden worldwide. Understanding how SARS-CoV-2 viral proteins behave in host cells can reveal underlying mechanisms of pathogenesis and assist in development of antiviral therapies. Here, the cellular impact of expressing SARS-CoV-2 viral proteins was studied by global proteomic analysis, and proximity biotinylation (BioID) was used to map the SARS-CoV-2 virus-host interactome in human lung cancer-derived cells. Functional enrichment analyses revealed previously reported and unreported cellular pathways that are associated with SARS-CoV-2 proteins. We have established a website to host the proteomic data to allow for public access and continued analysis of host-viral protein associations and whole-cell proteomes of cells expressing the viral-BioID fusion proteins. Furthermore, we identified 66 high-confidence interactions by comparing this study with previous reports, providing a strong foundation for future follow-up studies. Finally, we cross-referenced candidate interactors with the CLUE drug library to identify potential therapeutics for drug-repurposing efforts. Collectively, these studies provide a valuable resource to uncover novel SARS-CoV-2 biology and inform development of antivirals.

ISCA2 inhibition decreases HIF and induces ferroptosis in clear cell renal carcinoma.

Clear cell renal cell carcinoma (ccRCC), the most common form of kidney cancer, is typically initiated by inactivation of the von Hippel Lindau (VHL) gene, which results in the constitutive activation of the hypoxia inducible factors, HIF-1α and HIF-2α. Using a high throughput screen, we identify novel compounds that decrease HIF-1/2α levels and induce ferroptosis by targeting Iron Sulfur Cluster Assembly 2 (ISCA2), a component of the late mitochondrial Iron Sulfur Cluster (L-ISC) assembly complex. ISCA2 inhibition either pharmacologically or using siRNA decreases HIF-2α protein levels by blocking iron-responsive element (IRE)-dependent translation, and at higher concentrations, also decreases HIF-1α translation through unknown mechanisms. Additionally, ISCA2 inhibition triggers the iron starvation response, resulting in iron/metals overload and death via ferroptosis. ISCA2 levels are decreased in ccRCC compared to normal kidney, and decreased ISCA2 levels are associated with pVHL loss and with sensitivity to ferroptosis induced by ISCA2 inhibition. Strikingly, pharmacological inhibition of ISCA2 using an orally available ISCA2 inhibitor significantly reduced ccRCC xenograft growth in vivo, decreased HIF-α levels and increased lipid peroxidation, suggesting increased ferroptosis in vivo. Thus, the targeting of ISCA2 may be a promising therapeutic strategy to inhibit HIF-1/2α and to induce ferroptosis in pVHL deficient cells.

A BioID-derived proximity interactome for SARS-CoV-2 proteins.

The novel coronavirus SARS-CoV-2 is responsible for the ongoing COVID-19 pandemic and has caused a major health and economic burden worldwide. Understanding how SARS-CoV-2 viral proteins behave in host cells can reveal underlying mechanisms of pathogenesis and assist in development of antiviral therapies. Here we use BioID to map the SARS-CoV-2 virus-host interactome using human lung cancer derived A549 cells expressing individual SARS-CoV-2 viral proteins. Functional enrichment analyses revealed previously reported and unreported cellular pathways that are in association with SARS-CoV-2 proteins. We have also established a website to host the proteomic data to allow for public access and continued analysis of host-viral protein associations and whole-cell proteomes of cells expressing the viral-BioID fusion proteins. Collectively, these studies provide a valuable resource to potentially uncover novel SARS-CoV-2 biology and inform development of antivirals.

Comparative Application of BioID and TurboID for Protein-Proximity Biotinylation.

BioID is a well-established method for identifying protein-protein interactions and has been utilized within live cells and several animal models. However, the conventional labeling period requires 15-18 h for robust biotinylation which may not be ideal for some applications. Recently, two new ligases termed TurboID and miniTurbo were developed using directed evolution of the BioID ligase and were able to produce robust biotinylation following a 10 min incubation with excess biotin. However, there is reported concern about inducibility of biotinylation, cellular toxicity, and ligase stability. To further investigate the practical applications of TurboID and ascertain strengths and weaknesses compared to BioID, we developed several stable cell lines expressing BioID and TurboID fusion proteins and analyzed them via immunoblot, immunofluorescence, and biotin-affinity purification-based proteomics. For TurboID we observed signs of protein instability, persistent biotinylation in the absence of exogenous biotin, and an increase in the practical labeling radius. However, TurboID enabled robust biotinylation in the endoplasmic reticulum lumen compared to BioID. Induction of biotinylation could be achieved by combining doxycycline-inducible expression with growth in biotin depleted culture media. These studies should help inform investigators utilizing BioID-based methods as to the appropriate ligase and experimental protocol for their particular needs.

Simple and complex dysembryoplastic neuroepithelial tumors (DNT) variants: clinical profile, MRI, and histopathology.

INTRODUCTION: Dysembryoplastic neuroepithelial tumors (DNTs) are long-term epilepsy associated tumors subdivided into simple and complex variants. The purpose of this study was to relate different DNT components identified on magnetic resonance imaging (MRI) to histopathological features and to test the hypothesis that glial nodules as a histopathological feature of complex variants induce an occasional glioma misdiagnosis. METHODS: Clinical, MRI, and histopathologic features of DNTs operated between 1988 and 2008 were reviewed. RESULTS: From a total of 61 DNTs, 48 simple and 13 complex variants were identified. Multiple or single pseudocysts in a cortical/subcortical location with small cysts sometimes separated from the tumor represented the glioneuronal element and were found in all DNTs. FLAIR hyperintense tissue was found between pseudocysts but--in neocortical DNTs--also circumscript in deeper tumor parts. Calcification and hemorrhages in this location occurred in four of 13 complex variants, and one of these patients was also the only one with tumor growth. Patients with complex variants had earlier seizure onset, and complex variants were more often located outside the temporal lobe. Although complex variants represented a higher diagnostic challenge, misdiagnoses also occurred in simple variants. One of five of DNTs showed contrast enhancement, which varied on follow-up studies with enhancing parts becoming nonenhancing and vice versa. CONCLUSION: The glioneuronal element is readily identifiable on MRI and should be considered to support the DNT diagnosis. Complex DNT variants have a different clinical profile and a more variable histopathological and MRI appearance; however, misdiagnoses occasionally also occur in simple variants.

Reducing Mcl-1 gene dosage induces dopaminergic neuronal loss and motor impairments in Park2 knockout mice.

Mutations in the PARK2 gene are associated with early onset Parkinsonism. The Park2 -/- mouse, however, does not exhibit neurodegeneration or other Parkinson's disease (PD) phenotypes. Previously, we discovered that translation of Mcl-1, a pro-survival factor, is upregulated in the Park2 -/- mouse, suggesting a compensatory mechanism during development. Here we generated the Park2 -/- Mcl-1 +/- mouse and show that by reducing Mcl-1 gene dosage by 50%, the Park2 -/- genotype is sensitized, conferring both dopaminergic neuron loss and motor impairments. We propose that this murine model could be a useful tool for dissecting PD etiology and developing treatment strategies against this neurodegenerative disease.

Zika Virus Infection of Human Mesenchymal Stem Cells Promotes Differential Expression of Proteins Linked to Several Neurological Diseases.

The recent microcephaly outbreak in Brazil has been associated with Zika virus (ZIKV) infection. The current understanding of damage caused by ZIKV infection is still unclear, since it has been implicated in other neurodegenerative and developmental complications. Here, the differential proteome analysis of human mesenchymal stem cells (hMSC) infected with a Brazilian strain of ZIKV was identified by shotgun proteomics (MudPIT). Our results indicate that ZIKV induces a potential reprogramming of the metabolic machinery in nucleotide metabolism, changes in the energy production via glycolysis and other metabolic pathways, and potentially inhibits autophagy, neurogenesis, and immune response by downregulation of signaling pathways. In addition, proteins previously described in several brain pathologies, such as Alzheimer's disease, autism spectrum disorder, amyotrophic lateral sclerosis, and Parkinson's disease, were found with altered expression due to ZIKV infection in hMSC. This potential link between ZIKV and several neuropathologies beyond microcephaly is being described here for the first time and can be used to guide specific follow-up studies concerning these specific diseases and ZIKV infection.

Fourth ventricle neurocysticercosis: A case report.

BACKGROUND: Neurocysticercosis (NCC) is the most common helminthic disease of the nervous system in humans and it is caused by the larvae of the pork tapeworm, Taenia solium. We present a case of microsurgical removal of a fourth ventricle NCC cyst combined with an endoscopic third ventriculostomy (ETV) to treat hydrocephalus. CASE DESCRIPTION: A 36-year-old woman presented to the emergency room with headache and decreased visual acuity over the last 4 months. A brain magnetic resonance imaging showed obstructive hydrocephalus apparently correlated to a mobile, cystic lesion of the fourth ventricle. In the same operative time, an ETV and a suboccipital craniotomy were performed in order to remove the lesion and to treat the hydrocephalus. The cyst was completely removed and pathologically identified as a T. solium cyst. The early postoperative course was uneventful and she was discharged asymptomatic and off anthelmintic medication. Five weeks later, the patient returned with hydrocephalus recurrence and was successfully retreated with an ETV. At 5-month follow-up, she remains asymptomatic and has no evidence of persistent disease or hydrocephalus recurrence. CONCLUSION: Intraventricular neurocysticercosis is, typically, a surgical disease. For cysts located on the fourth ventricle, a suboccipital craniotomy and a telovelar approach remains a valid option. Cyst removal does not necessarily resolve the hydrocephalus problem. ETV offers an option to the classic shunt placement approach and was shown to be effective even on hydrocephalus recurrence.

Oncogenic mutations in IKKß function through global changes induced by K63-linked ubiquitination and result in autocrine stimulation.

Mutations at position K171 in the kinase activation loop of Inhibitor of κB kinase beta (IKKß) occur in multiple myeloma, spleen marginal zone lymphoma and mantle cell lymphoma. Previously, we demonstrated that these result in constitutive kinase activation and stimulate Signal Transducer and Activator of Transcription 3 (STAT3). This work also identified K147 as a site of K63-linked regulatory ubiquitination required for activation of signaling pathways. We now present a more detailed analysis of ubiquitination sites together with a comprehensive examination of the signaling pathways activated by IKKß K171E mutants. Downstream activation of STAT3 is dependent upon the activity of: UBE2N, the E2 ubiquitin ligase involved in K63-linked ubiquitination; TAK1 (MAP3K7), or TGFß Activated Kinase, which forms a complex required for NFκB activation; JAK kinases, involved proximally in the phosphorylation of STAT transcription factors in response to inflammatory cytokines; and gp130, or IL-6 Receptor Subunit Beta which, upon binding IL-6 or other specific cytokines, undergoes homodimerization leading to activation of associated JAKs, resulting in STAT activation. We further demonstrate, using an IL-6-responsive cell line, that IKKß K171E mutants stimulate the release of IL-6 activity into conditioned media. These results show that IKKß K171E mutants trigger an autocrine loop in which IL-6 is secreted and binds to the IL-6 receptor complex gp130, resulting in JAK activation. Lastly, by examining the differential abundance of proteins associated with K63-only-ubiquitinated IKKß K171E, proteomic analysis demonstrates the global activation of proliferative responses. As cancers harboring K171-mutated IKKß are likely to also exhibit activated STAT3 and p44/42 MAPK (Erk1/2), this suggests the possibility of using MAPK (Erk1/2) and JAK inhibitors, or specific ubiquitination inhibitors. K63-linked ubiquitination occurs in other kinases at sites homologous to K147 in IKKß, including K578 in BRAF V600E, which serves as an oncogenic driver in melanoma and other cancers.

VRK2A is an A-type lamin-dependent nuclear envelope kinase that phosphorylates BAF.

The nuclear envelope (NE) is critical for numerous fundamental cellular functions, and mutations in several NE constituents can lead to a heterogeneous spectrum of diseases. We used proximity biotinylation to uncover new constituents of the inner nuclear membrane (INM) by comparative BioID analysis of lamin A, Sun2 and a minimal INM-targeting motif. These studies identify vaccinia-related kinase-2 (VRK2) as a candidate constituent of the INM. The transmembrane VRK2A isoform is retained at the NE by association with A-type lamins. Furthermore, VRK2A physically interacts with A-type, but not B-type, lamins. Finally, we show that VRK2 phosphorylates barrier to autointegration factor (BAF), a small and highly dynamic chromatin-binding protein, which has roles including NE reassembly, cell cycle, and chromatin organization in cells, and subtly alters its nuclear mobility. Together these findings support the value of using BioID to identify unrecognized constituents of distinct subcellular compartments refractory to biochemical isolation and reveal VRK2A as a transmembrane kinase in the NE that regulates BAF.

Oncogenic Gene Fusion FGFR3-TACC3 Is Regulated by Tyrosine Phosphorylation.

UNLABELLED: Fibroblast growth factor receptors (FGFR) are critical for cell proliferation and differentiation. Mutation and/or translocation of FGFRs lead to aberrant signaling that often results in developmental syndromes or cancer growth. As sequencing of human tumors becomes more frequent, so does the detection of FGFR translocations and fusion proteins. The research conducted in this article examines a frequently identified fusion protein between FGFR3 and transforming acidic coiled-coil containing protein 3 (TACC3), frequently identified in glioblastoma, lung cancer, bladder cancer, oral cancer, head and neck squamous cell carcinoma, gallbladder cancer, and cervical cancer. Using titanium dioxide-based phosphopeptide enrichment (TiO2)-liquid chromatography (LC)-high mass accuracy tandem mass spectrometry (MS/MS), it was demonstrated that the fused coiled-coil TACC3 domain results in constitutive phosphorylation of key activating FGFR3 tyrosine residues. The presence of the TACC coiled-coil domain leads to increased and altered levels of FGFR3 activation, fusion protein phosphorylation, MAPK pathway activation, nuclear localization, cellular transformation, and IL3-independent proliferation. Introduction of K508R FGFR3 kinase-dead mutation abrogates these effects, except for nuclear localization which is due solely to the TACC3 domain. IMPLICATIONS: These results demonstrate that FGFR3 kinase activity is essential for the oncogenic effects of the FGFR3-TACC3 fusion protein and could serve as a therapeutic target, but that phosphorylated tyrosine residues within the TACC3-derived portion are not critical for activity. Mol Cancer Res; 14(5); 458-69. ©2016 AACR.

[Subdural empyema due to gemella morbillorum as a complication of acute sinusitis]. / Empiema subdural a gemella morbillorum como complicação de sinusite aguda.

Subdural empyema is a life-threatening infection that may complicate acute sinusitis. The authors report the case of a previously healthy 10 year-old girl who presented with subdural empyema due to Gemella morbillorum after an untreated maxillary, ethmoidal and esphenoidal sinusitis. Despite immediate drainage of the empyema and underlying primary infection and treatment with broad spectrum antibiotics, she later developed frontal cerebritis and refractory intracranial hypertension, needing urgent decompressive craniectomy. She recovered gradually, maintaining to date slight right hemyparesis and aphasia. Even though it is considered a low virulence organism, G. morbillorum has been increasingly described in central nervous system infection. In this case, the prompt institution of broad spectrum antibiotics and surgical drainage, as well as the agressive treatment of complications, including decompressive craniectomy, were crucial to the patient's recovery.

The basal temporal approach for mesial temporal surgery: sparing the Meyer loop with navigated diffusion tensor tractography.

BACKGROUND: Visual field defects are a common side effect after mesial temporal resections such as selective amygdalohippocampectomy (SelAH). OBJECTIVE: To present a method of diffusion tensor tractography (DTT) of the Meyer loop for preoperative planning of the surgical approach for SelAH and for intraoperative visualization on a navigation-guided operating microscope. METHODS: Twelve patients were selected for SelAH to treat mesial temporal lobe epilepsy. All received preoperative MRI with diffusion tensor imaging sequences. The Meyer loop was determined and reconstructed as an object with DTT. Images were utilized for preoperative planning in which a safe approach not affecting the Meyer loop was specified. A navigation-guided operating microscope was used for image-guided surgery. RESULTS: DTT was a reliable method for visualization of the Meyer loop. Reconstruction of the Meyer loop had a direct impact on the approach planning. In all 12 cases, the optic tract could only be spared using a basal approach. Ten patients underwent SelAH by the subtemporal approach, and 2 underwent SelAH by the transcortical approach through the inferior temporal gyrus. During the critical early phase of the operation image guidance remained accurate until entry into the ventricle. Nine of 12 patients had no postoperative field deficits (75%). Three patients (25%) experienced peripheral incomplete quadrantanopia. CONCLUSION: DTT and intraoperative visualization of the Meyer loop is a helpful tool for preoperative planning and during surgery to find a safe trajectory to mesial temporal structures while avoiding the optic radiation. This technique in combination with a basal approach seems to be a promising strategy to prevent postoperative visual field deficits in most patients.